Well, I've had the inverted alpha in saved pngs, tifs and psd files with pz3 and animation frames both now, so Poser 5 has 2 out of 3 of the same old Poser 4 and ProPack glitches. I'm betting it has all 3, but like Poser 4, it was much rarer when exporting images.

BTW, I use pngs most of the time because the format is lossless with good compression that doesn't require a fee to use when you create images. Most anyone with a modern PC can view them no matter whether they have graphics software or not because most come with Windows and IE 4, 5.x or 6, all of which can view pngs. The fact that one can view them on the web, share them on a cd and expect most anyone can view them, and they are often smaller than a zipped uncompressed bitmap file (another well supported format in Windows) makes them a good choice. The alpha channel is a bonus when software supports it properly. Newer software has been disposing of the alpha channel and opening the images with transparent backgrounds. Perhaps you can open the image in an older app and invert the alpha but I can't do it in PSP 7.04 and I hear that Photoshop 7 can't do it either with a png that has an inverted alpha because it tosses out the alpha channel data upon loading so there is no alpha channel to invert. (not verified)